The invention relates to an improved sealing element for an encapsulated measuring device, especially an incremental or absolute length or angle measuring device, designed for accurate measurement in such environments as those of a laboratory, factory or workshop.
German Pat. No. 28 46 768 discloses an encapsulated measuring device in which a scale and a scanning unit are disposed in a housing, which defines an opening extending along the measuring direction, and which is closed by means of a pair of sealing elements arranged to cover the opening in a roof pattern in the form of plastic of rubber lips. A follower passes between the sealing lips and connects the scanning unit with an object to be measured. The follower is secured to the scanning unit at one end and to a slide piece at the other end.
In the aforementioned measuring system the sealing lips serve to seal the housing as hermetically as possible. They must lie closely on the follower and, therefore, are typically of elastic construction with a high restoring force. Due to frictional forces acting on the follower as a result of the high restoring forces of the sealing lips, the follower can undergo deformations in the measuring direction which are detrimental to measuring accuracy. Deformations of the sealing lips also occur along the measuring direction, so that even when the follower is sword-shaped in cross section, small openings in the sealing lips are often formed adjacent to the follower.
Thus, there presently exists a need for an improved sealing element for such measuring devices, which will minimize deformations of the follower and of the sealing lips.